The prior art includes showings of load stabilizers mounted as attachments on fork lift trucks. U.S. Pat. No. 3,174,639 to Chase et al., shows a positionable upper frame which telescopes laterally to stabilize the upper end of a load against tipping. U.S. Pat. No. 3,455,476 to Grigsby shows a horizontal arm which supports the outer end of a load to hold it up and stabilize it, but not as a downward acting clamp. U.S. Pat. No. 2,578,802 to Heidrick et al., shows a downward clamping frame which impales baled hay to clamp it. U.S. Pat. No. 3,433,376 to Jordan, shows sidewardly acting frames for grabbing and supporting a load using resiliently faced grab members, but not downwardly cooperating with lift forks by clamping downwardly theretoward. U.S. Pat. No. 3,563,341 to Bultman shows a fork lift jack without a clamping frame but wherein the main fork supporting carriage is driven by pinion means running against stationary racks supported on the main lift frame.